Flow processing system

ABSTRACT

A flow processing system for processing disc-shaped articles such as discs to be used to produce video or audio disc masters, whereby a plurality of processing units for performing respectively different processing operations are combined into a single system in which each disc is moved only horizontally and in a continuously rotating condition, both during processing and while being moved between the processing units. In addition, the supporting structure of the processing units is implemented such as to produce no disturbances in a horizontally directed dust-excluding flow of air, to ensure maximum prevention of adherence of dust particles to the disc surfaces.

This application is a continuation of application Ser. No. 07/323,834,filed Mar. 15, 1988 which is a continuation of application Ser. No.07/094,994 filed Sept. 10, 1987, now U.S. Pat. No. 4,850,791.

BACKGROUND OF THE INVENTION

The present invention relates to an apparatus for performingpredetermined processing within a clean room of disc-shaped articles,such as discs to be used for video or audio recording.

Optical recording is widely utilized for recording video, audio andother data, with the recording medium being in the form of discs. In theoptical recording method, a photoresist is coated on a glass disc whichserves as a substrate, to thereby produce a disc which can be utilizedto produce a disc master. Light from a laser beam, focussed to a minutespot, is caused to fall upon the resist film thus formed on the glassdisc, in accordance with video or audio data, etc. This process isreferred to as the bit-by-bit method of light exposure. The disc issubsequently developed to produce a disc master, in which surface pitsare formed whose lengths and repetition period constitute the recordeddata.

For convenience of description, a glass disc as described above which isin the condition prior to having a film of photoresist formed thereonwill be referred to in the following simply as a glass disc, while adisc which has a film of photoresist formed thereon will be referred toas a resist-coated disc.

With such a method, it is necessary to execute several processing stepsin order to prepare a resist-coated disc, i.e. washing of the glassdisc, coating the disc with primer (in order to enhance the degree ofadherence of the photoresist to the disc surface), photoresist coating,and baking (i.e. thermal processing). During these processing steps, itis essential that all dust be excluded, and for this reason theprocessing is performed entirely within a clean room. Furthermore, evenwithin the interior of a clean room, minute particles of dust which havenot been removed by the filters will remain floating in the atmosphere.In order to prevent these minute dust particles from adhering to thedisc surface, a current of air is blown across the glass disc and theresist-coated disc while processing is being carried out on the discs.However it has been found in practice that a sufficiently high degree ofdust exclusion effectiveness cannot be attained by such a flow of airalone, due to disturbances which arise within the air flow.

Moreover in the prior art, each of the processing steps described aboveis executed by a separate processing unit, with the discs generallybeing manually transferred between these processing units following eachprocessing step. As a result, the overall system size is large, and therate of productivity is low.

SUMMARY OF THE INVENTION

It is an objective of the present invention to overcome the problems ofthe prior art described above, by providing a flow processing system fordisc-shaped articles whereby an effective air flow is continuouslymaintained, to thereby maintain a sufficiently high degree of dustexclusion effectiveness of the air current.

It is a further objective of the present invention to provide a flowprocessing system for disc-shaped articles which is compact in size andenables enhanced productivity to be attained.

To attain the above objectives, a flow processing system according tothe present invention including a plurality of processing units forexecuting respectively different processing operations on disc-shapedarticles which are rotated by a turntable, the plurality of processingunits being supported by a single frame, comprises a turntable unitincluding the turntable and a drive source for rotating the turntable,guidance means mounted on the frame for guiding the turntable unitbetween the plurality of processing units, and drive means for movingthe turntable unit between the plurality of processing units, and ischaracterized in that rotational drive applied to the turntable iscontinued while the turntable is being moved between the processingunits.

A flow processing system according to the present invention is furthercharacterized in that the processing units are supported upon the frameby supporting means which do not produce any disturbances in a flow ofair which is directed substantially horizontally towards the disc-shapedarticles during processing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an oblique view of a flow processing system according to thepresent invention, for coating glass discs with photoresist;

FIGS. 2 and 3 are respectively a partial cross-sectional view inelevation and a partial cross-sectional view in plan of a specificconfiguration for the apparatus of FIG. 1;

FIG. 4 is a cross-sectional view of a specific configuration for aturntable unit shown in FIGS. 2 and 3;

FIG. 5 is a plan view to illustrate an arrangement whereby two systemsaccording to the present invention are positioned at the right and leftsides of an operator;

FIG. 6 is a table setting out relationships between outputs producedfrom an array of position sensors and corresponding positions of aturntable;

FIG. 7 is a flow chart of an operating sequence for preparingresist-coated discs.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention will be described in thefollowing, referring to the drawings. FIG. 1 is an oblique view of theembodiment, which is a flow processing system for preparing discs to beused as disc masters, by forming a film of photoresist upon the glassdiscs. Numeral 1 denotes an apparatus unit which functions as a "wetstage", for executing processing steps consisting of washing the glassdiscs, primer processing, and photoresist coating. The system furtherincludes an apparatus unit 2 which constitutes an inspection stagewhereby the glass discs are inspected for defects, the resist-coateddiscs are inspected for defects, and the film thickness on theresist-coated discs is measured. Numeral 3 denotes an apparatus unitfunctioning as a baking stage, for executing pre-bake processing. Theflow processing system which is thus configured of the apparatus units 1to 3 is contained within a clean room. With this flow processing systemthe operations of washing and primer processing the glass discs,inspecting the glass discs, coating the discs with photoresist, thermalprocessing, inspection of the resist-coated discs for faults, andinspection of the film thickness of the resist-coated discs, areexecuted automatically as a continuous process flow.

The machined and washed glass discs (not shown in the drawings) aretemporarily stored in a wet stock chamber 4, in which ultrasonic washingetc. is executed to maintain the discs in optimum condition. Next, eachdisc is automatically transported, in a substantially horizontalorientation, to the apparatus unit 1, in which the processing sequencedescribed above is executed with the disc being maintained in ahorizontal position throughout. On completion of this processingsequence, the disc is transported out of the apparatus unit 3. A cleanbench 5 is disposed at the left side of the apparatus, with respect tothe direction of processing flow from the apparatus unit 1 to theapparatus unit 3. A flow of air is sent from the clean bench 5 in asubstantially horizontal direction towards the glass disc which isundergoing the processing sequence described above. As a result, minuteparticles of dust etc. which have not been removed by filtering and arefloating in the atmosphere, are prevented from adhering to the surfaceof the glass disc. The operator of the apparatus is positioneddownstream from the apparatus units 1 to 3 in the air current from theclean bench 5.

The specific configuration of the apparatus units 1 to 3 will bedescribed referring to FIGS. 2 to 4.

A glass disc 6 is supported in a substantially horizontal orientation bya turntable 7. The turntable 7, a motor 8 serving as a drive source, anda belt 9 which transfers rotational force from the motor 8 to theturntable 7 constitute a turntable unit 10. The turntable unit 10 ismounted upon a pair of guide rails 12a and 12b which are disposedmutually parallel and run between the apparatus units 1 to 3 and aremounted on an upper face of a frame 11. The turntable unit 10 is movablebetween the apparatus units 1 to 3 by means of a rear bearing (not shownin the drawings). A threaded shaft 13 is rotatably mounted on the upperface of the frame 11, aligned parallel to the guide rails 12a and 12band extending substantially along the range of movement of the turntableunit 10. The threaded shaft 13 is engaged in a nut 14 which is attachedto the turntable unit 10. The threaded shaft 13 is rotated by beingdriven by a transport motor 15, whereby the turntable unit 10 is movedalong a direction which is determined by the direction of rotation ofthe shaft 13.

As shown in FIG. 4, the turntable 7 is attached to a top portion of aspindle 16 having a central bore 16a formed therein. The spindle 16 isaligned with a central axis of the turntable 7, and is rotatably mountedwith respect to a housing 18 by a bearing 17, with a large pulley 19being fixedly attached to the lower end of the spindle 16. The largepulley 19 and a small pulley 21, which is fixedly mounted on the driveshaft of a motor 8, are linked by a belt 9 for driving the large pulley9 by the motor 8. Due to the use of this belt drive configuration, avacuum seal 20 which is attached to the lower end of the spindle 16 canbe easily replaced. More specifically, if a direct drive configurationwere to be used, it would be necessary to remove heavy components suchas the motor 8 each time that the vacuum seal 20 has to be replaced,which would be extremely troublesome. However by using a drive beltarrangement this problem is avoided, and changing of the vacuum seal 20can be easily carried out.

A receiving stage 21 is fixedly mounted around the periphery of theturntable 7, with the diameter of the receiving stage 21 being largerthan the largest diameter of the glass disc 6. A pair of size sensors22a, 22b are mounted on the receiving stage 21, positioned along aradius of the glass disc 6. The size sensors 22a, 22b serve to detectthe size of the glass disc 6. A pair of type sensors 23a, 23b aremounted in the vicinity of the central aperture of the receiving stage21, for detecting the type of the glass disc 6. A center cap 24 ismounted to cover the upper end of the spindle 16.

As shown in FIGS. 2 and 3, a cap 25 is incorporated, which can be movedupward and downward with respect to the frame of the apparatus unit 1.The cap 25 is normally maintained in an upper position, such as not toobstruct movement of the turntable unit 10. When processing is to beexecuted by the apparatus unit 1, the cap 25 is driven to a loweredposition by a linear drive motor 27, acting through a linking member 26(shown in FIG. 1). It should be noted that the present invention is notlimited to the use of the linear motor 27 as a drive source for the cap25, and that various other drive means could be utilized for thispurpose, so long as these are capable of driving the cap 25 to upper andlower positions. When the cap 25 is in the lower position, it fitstightly around the periphery of the receiving stage 21, to establish atightly sealed condition. In this condition, the glass disc 6 is held incontact with the turntable 7 by vacuum suction produced by the action ofa vacuum pump 28, while being rotated by motor 8 and subjected towashing by a washing fluid which is ejected from a nozzle (not shown inthe drawings) which is mounted within the cap 25. Upon completion ofthis washing process, primer processing is performed. On completion ofthe washing and primer processing, the turntable unit 10 carrying theglass disc 6 is moved along the guide rails 12a and 12b to the apparatusunit 2.

The apparatus unit 2 consists of an inspection unit 29, and two pillars30a and 30b for supporting the inspection unit 29, together with a hood31 covering the inspection unit 29. The two pillars 30a and 30b alsofunction as ducts (e.g. wiring ducts for accommodating electricalcables, etc.) and are positioned downstream in the air flow from theglass disc 6, i.e. are positioned on the opposite side of the apparatusfrom the clean bench 5. As a result of this arrangement, no disturbancesdue to the supporting means for the inspection unit 29 are produced inthe flow of air which is sent in a direction parallel to the glass disc6 from the clean bench 5, to thereby maintain the effectiveness of thisair flow in preventing adherence of dust particles to the surface of theglass disc 6. The glass disc 6 which has been subjected to washing andprimer processing is inspected for scratches or other defects by theinspection unit 29 of the apparatus unit 2. In addition, after a dischas been subjected to thermal processing in the apparatus unit 3, theresultant resist-coated disc is inspected by the inspection unit 29 ofapparatus unit 2 for scratches or other surface defects, and at the sametime the thickness of the film of photoresist which has been formed onthe disc surface is measured.

The apparatus unit 3 incorporates a processing unit consisting of abaking unit 32 which is supported on the frame 11 by a pair of pillars33a and 33b and is covered by a hood 34. As in the case of the apparatusunit 2, the pillars 33a and 33b also function as ducts and arepositioned downstream from the disc being processed, with respect to theair flow which is sent from the clean bench 5 as described above.Pre-bake processing is performed on the resist-coated disc which hasbeen previously coated with photoresist. This pre-bake processing isexecuted by applying radiation which is in the far infra-red range.During the pre-bake processing, the surface temperature of theresist-coated disc is measured by a radiation thermometer 35, with thesurface temperature being controlled on the basis of the measuredtemperature.

As will be clear from FIG. 1, the hoods 31 and 34 shown in FIGS. 2 and 3are respectively positioned close to the clean bench 5, with a portionof the top face of each hood (adjacent to the side of the hood which isclosest to the clean bench 5) being shaped to slope downwards, and withportions of two opposing side faces of each hood (i.e. portions whichare adjacent to the aforementioned side of the hood) being shaped toslope towards a central position between these opposing side faces. As aresult, as indicated by the arrows in FIGS. 1 and 3, the air flow whichis sent from the clean bench 5 is caused to flow in a satisfactorymanner, in the region of that air flow which is downstream from theaforementioned sloping portions of the upper and side faces of each ofhoods 31 and 34. In this way a satisfactory air flow, free fromdisturbances, is maintained around the glass discs and the resist-coateddiscs, both during processing and inspection and during movement of thediscs between the processing units.

As described in the above, the inspection unit 29, the hood 31, thebaking unit 32, and the hood 34 are respectively supported on pillars30a, 30b, and 33a, 33b respectively, and are positioned downstream withrespect to the glass disc 6 in the air flow. As shown in FIG. 3, thepillars 30a and 30b and the pillars 33a and 33b are respectivelyretained in retaining apertures 37a, 37b and 38a, 38b which are formedin the upper face of the frame 11. If a pair of systems according to thepresent invention are to be used together, disposed respectively at theright and left sides of an operator, then it will in general benecessary to position the clean bench 5 of one system on the oppositeside of the frame 11 from that shown in FIG. 1. If that were to be done,using the arrangement shown in FIG. 1, then the pillars 30a and 30b and33a and 33b of one system will be positioned upstream in the air flowfrom the clean bench 5 of that system, with respect to a disc beingprocessed. Furthermore the sloping faces of the hoods 31 and 34 of onesystem would be positioned downstream from the air flow, therebypreventing a smooth flow. As a countermeasure against this, the pillars30a and 30b and the pillars 33a and 33b are supported such as to befreely removable from the retaining apertures 37a, 37b and 38a, 38brespectively, and to be capable of being inserted into an oppositelypositioned set of retaining apertures 39a, 39b and 40a, 40brespectively. In this way the most suitable positions for the pillars30a and 30b and the pillars 33a and 33b can be selected as required, sothat as shown in FIG. 5 the pillars 30a and 30b and the pillars 33a and33b can be always positioned downstream with respect to the glass disc6, and the sloping faces of the hoods 31 and 34 can be positionedupstream in the air flow.

As shown in FIG. 2, a set of six position sensors 36a to 36f are arrayedalong the direction of movement of the turntable unit 10, mounted on theframe 11, for sensing the position of the turntable unit 10 along thedirection of movement thereof. Two of these position sensors 36a to 36fare provided for each of the apparatus units 1 to 3, and the position ofthe turntable unit 10 is detected based upon a combination of outputsproduced from these position sensors 36a to 36f. More specifically, asshown in FIG. 6, a condition in which only the position sensors 36a and36b are in the ON state indicates that the turntable unit 10 ispositioned at the apparatus unit 1, a condition in which only theposition sensors 36c and 36d are in the ON state indicates that theturntable unit 10 is positioned at the apparatus unit 2, and a conditionin which only the position sensors 36e and 36f are in the ON stateindicates that the turntable unit 10 is positioned at the apparatus unit3. When the turntable unit 10 is positioned at one end of its range oftravel, this is indicated by only one of the position sensors 36a or 36fbeing in the ON state. When the turntable unit 10 is in an intermediateposition between apparatus units, then this is indicated by a conditionin which only the position sensors 36b and 36c or only the positionsensors 36d and 36e are in the ON state.

By detecting the position of the turntable unit 10 in this way, on thebasis of combinations of outputs produced from the position sensors 36ato 36f, the turntable unit 10 can be accurately and reliably halted atthe appropriate working positions of the apparatus. Furthermore if forexample a power supply failure should occur while the turntable unit 10is in the process of being moved, then immediately following therestoration of power, the appropriate direction in which the turntableunit 10 is to be moved can be immediately determined on the basis of theoutputs from the position sensors, so that rapid restoration ofoperation can be smoothly executed after a power failure has occurred.

With the system configuration described above, control of movement ofthe turntable unit 10, determination of the positions at which theturntable unit 10 is to be halted, control of the processing operationsexecuted by each of the apparatus units 1 to 3, and control of theturntable 7, can be performed automatically, for example by means of asystem controller (not shown in the drawings) based on a microcomputer.

The operating sequence which is executed by this embodiment of thepresent invention will be described referring to the flow chart of FIG.7.

Firstly, when a glass disc has been placed on the turntable 7 at thestart of processing by the apparatus unit 1, the cap 25 is moveddownward to engage with the receiving stage 21 of the turntable unit 10to thereby establish a tightly sealed condition. Cleansing of the glassdisc is then carried out in this condition (step S1). Primer processingis then carried out (step S2). With the glass disc which has beensubjected to washing and primer processing still mounted on theturntable 7, the turntable unit 10 is then moved to the apparatus unit2, and the glass disc is inspected for defects (step S3). If the discpasses this inspection, it is then moved back to the apparatus unit 1,and photoresist processing is carried out (step S4), to convert the discto a resist-coated disc. This resist-coated disc is then moved on theturntable unit 10 past the apparatus unit 2 to the apparatus unit 3, andis subjected to pre-bake processing by far infra-red radiation (stepS5). Upon completion of this thermal processing, the resist-coated discis again moved to the apparatus unit 2 to be inspected for defects andfor measurement of the thickness of the photoresist film (step S6). Thiscompletes the processing sequence for preparing a resist-coated disc.

Each of the above processing steps which are performed by the apparatusunits 1 to 3 is of course carried out while the turntable 7 is beingrotated. Furthermore with the system of the present invention, thisrotation of the turntable 7 is also continued while the turntable 7 isbeing moved between the apparatus units 1 to 3. In this way the glassdisc or resist-coated disc is continuously rotated at all times, therebyserving to further prevent the adherence of particles of dust etc. onthe disc surface. Furthermore since it is not necessary for time to betaken to move the turntable 7 upward each time it is moved to one of theapparatus units 1 to 3, movement between the various processing stepscan be smoothly executed.

In the embodiment described above, the present invention is applied toan apparatus for preparing resist-coated discs, by processing glassdiscs. However it should be noted that the present invention is notlimited to such an application, and can be applied to various types ofapparatus for executing specific processing operations on thin flatarticles. Furthermore with the embodiment described above, a pluralityof processing units are combined into a single system. However thepresent invention is of course applicable to an apparatus which isinherently configured as a single unit.

It can be understood from the above description that with a flowprocessing system for processing a disc-shaped article according to thepresent invention, as described hereinabove, pillars which support aprocessing unit with respect to a frame of the apparatus at a positionabove a disc-shaped article, are disposed downstream in an air flow withrespect to the article, whereby a satisfactory flow of air can bemaintained so that a satisfactory dust exclusion effect can be producedby the air flow.

What is claimed is:
 1. A flow processing system for use in a clean roomin which air-flow is circulated through filters for the removal of dustparticles, which comprises:a plurality of processing units forrespectively executing different processing operations on a disc-shapedarticle, said processing units being sequentially arranged along agenerally horizontal line; a turntable for carrying on a support surfacethereof said disc-shaped article to be processed; guidance means forrotatably carrying said turntable and for transporting said turntablefrom one processing unit to another along said line; drive means forcontinuously rotating said turntable both while said turntable ispositioned at one of said processing units and also while said turntablemoves from one of said processing units to another, to prevent minutedust particles in the atmosphere which have not been removed by thefilters from adhering to said disc-shaped article while processing isbeing carried out on said disc-shaped article; and air-flow generatingmeans located along one side of said line of processing units, forgenerating an additional air-flow in the clean room directed over andessentially parallel to the support surface of said continuouslyrotating turntable and the disc-shaped article thereon transversely ofsaid line of processing units and so as to encompass an area coveringall of said processing units, as well as spaces between said processingunits, thereby providing a disturbance free continuous air-flow acrossand between the processing units so as to encompass the entire distancetraveled by the turntable during processing of said disc-shaped articleand further prevent the minute dust particles in the atmosphere whichhave not been removed by the filters from adhering to said disc-shapedarticle while processing is being carried out on said disc-shapedarticle.
 2. A flow processing system according to claim 1, in which saidprocessing units are arranged along a straight line.
 3. A flowprocessing system according to claim 1, in which all of said processingunits are accessible to an operator from an opposite side of said lineof said processing units and downstream of said additional air-flowproduced by said air-flow generating means.